This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. In collaboration with Dr. Paul Smith of Cardiff University, we will characterize the emission spectra of a new class of DNA binding dyes that are rapidly cell permeable and excite in the far red. The Cardiff group has characterized these dyes with a combination of conventional flow measurements, fluorescence spectroscopy of bulk samples and live cell spectral imaging. We will use stained cell lines to characterize the performance of the spectral instrument in the NIR region as compared to the other measurements. We will also use the improved PS cytometer to investigate changes in lifetime of these dyes upon DNA binding, potentially enabling separation of bound and unbound flurorophore in situ.